1. Field of the Invention
The invention relates to a method for the laser machining of coated sheets. A method of this type is already known from DE 44 07 190 A1.
2. Related Art of the Invention
With many coated sheets, in particular zinc-coated sheets as used in the automobile industry, the coating material has a markedly lower boiling point than the melting point of the sheet material. When sheets of this type are laser-welded in a lap joint, this leads to explosive vaporizations of coating material, which seriously affect the quality of the joint.
In order to improve the joint quality, it has already been proposed to use spacers to create narrow gaps between the sheets, into which the vaporized coating material can escape. Suitable crater-shaped spacers can be generated, according to JP 11-047967, by laser bombardment of the surface. According to DE 44 07 190 A1, knurling-type spacers can be produced by means of a laser scanner device.
The primary drawback in this is the relatively long time necessary for the machining, which, especially in mass production, creates considerable costs.